Musannaf Ibn Abi Shayba 13:923

Abu Bakr narrated to us, he said: Abd al-A’la narrated to us, from Ma’mar, from al-Zuhri, regarding the slave who buys and sells without the permission of his master. He said: There is nothing upon his master. It is the liability of the slave; if he is emancipated, then it is upon him.